The straight in a smile’s crooked lines

So much reads straight in a smile’s crooked lines:
One betrays care, fear of the enemy —
tough, big, or swindler — crouching at the door;
Another knows where the enemy hides,
And, that presently the bastard will be
Knocked out cold upon the doorstep.
If you smile, friend, follow that second line;
The first is to cast your pearls before swine.